1. Field of the Invention
The present invention relates to caller identification systems.
2. Background of the Related Art
Caller identification (referred to as caller ID), or calling number identification, is a telephone service that provides a caller's telephone number to a called party's telephone during the ringing signal or as the call is set up. Some telephone services will also provide the called party's telephone with a name associated with the calling telephone number. Typically, called party's telephone will display the calling party's telephone number and/or name, so that the called party may determine whether or not to answer the call. Still further, the called party's telephone may store caller ID records so that the called party's telephone can easily retrieve and use the calling party's telephone number in the future.
Although the implementation of caller ID provides tremendous advantages for many users, there are instances where a user may prefer not to share their telephone number and name with a called party. Accordingly, telephone service providers may offer a privacy feature, such as the vertical service code “*67” which blocks presentation of the caller ID information to the called party's telephone. If the user wants to block their caller ID information from being presented to any called party's telephone, then the user may register their telephone number as a “private number” with the telephone service provider.
The availability of caller ID has also allowed users to block calls from undesired originating telephone numbers. For example, telephone service providers may allow a user block calls by registering a list of blocked telephone numbers with the telephone service provider. When a call is directed to the user's telephone number, the telephone service provider searches any registered list of blocked number to determine whether or not to forward the call to the user's telephone. If the calling party's telephone number is on the called party's registered block list, then the call is immediately dropped. In this manner, a user can avoid repeated calls from disfavored marketers or harassing individuals.
However, individuals and companies whose calls have been blocked may resort to caller ID spoofing in which the caller ID information is altered so that the call appears to originate from a different caller, or at least avoids the user's registered block list. Although spoofing may be illegal is some contexts, individual users are unlikely to take independent legal action and simply prefer to avoid receiving such calls.